Enable the "Browse the Physical Web" button only when Physical Web is ON.

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebDiagnosticsPage.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.physicalweb;
 
 import android.app.Activity;
 import android.content.Intent;
 import android.content.res.Resources;
 import android.os.Build;
@@ skipping 117 matching lines @@
         boolean isOnboarding = PhysicalWeb.isOnboarding();
 
         int prerequisitesResult = Utils.RESULT_SUCCESS;
         if (!isSdkVersionCorrect
                 || !isDataConnectionActive
                 || bluetoothStatus == Utils.RESULT_FAILURE
                 || !isLocationServicesEnabled
                 || !isLocationPermissionGranted
                 || !isPreferenceEnabled) {
             prerequisitesResult = Utils.RESULT_FAILURE;
+            mLaunchButton.setEnabled(false);
         } else if (bluetoothStatus == Utils.RESULT_INDETERMINATE) {
             prerequisitesResult = Utils.RESULT_INDETERMINATE;
+            mLaunchButton.setEnabled(false);
         }
 
         sb.append("<h2>Status</h2>");
 
         sb.append("Physical Web is ");
         appendResult(sb, prerequisitesResult != Utils.RESULT_FAILURE, "ON", "OFF");
 
         sb.append("<h2>Prerequisites</h2>");
 
         sb.append("Android SDK version: ");
@@ skipping 67 matching lines @@
 
     private static Intent createListUrlsIntent() {
         return new Intent(ContextUtils.getApplicationContext(), ListUrlsActivity.class)
                 .putExtra(ListUrlsActivity.REFERER_KEY, ListUrlsActivity.DIAGNOSTICS_REFERER);
     }
 
     private static String colorToHexValue(int color) {
         return "#" + Integer.toHexString(color & 0x00ffffff);
     }
 }